This invention relates to a solar energy absorber and more particularly to using multiple glass layers for reducing the heat loss through re-radiation from the heat absorbing surfaces by circulating a heat conducting fluid between intermediate layers of glass to carry away the re-radiation heat.
Heretofore, most systems designed to trap solar energy utilized a system often called "the green house effect". In such systems, visible radiation passes through one or more transparent outer covers and is almost entirely absorbed by an absorptive surface. The absorptive surface was usually constructed of tubing wherein a fluid must pass therethrough for transferring thermal energy absorbed by conduction. The outer cover, while transparent to visible radiation is largely opaque to infrared radiation off of the absorber surface, and hence, absorbs it. It conducts the energy that is not re-radiated to the absorber surface through the outer cover where it is convected or re-radiated away. Examples of such a system are shown in U.S. Pat. No. 3,077,190 and U.S. Pat. No. 2,969,788.
For a given absorptive surface, the amount of thermal energy lost by convection or re-radiation is a function of the outer cover temperature. Often more than one outer cover is used to reduce the infrared energy reaching and, consequently, heating the final cover.